Thermal Retention Structure for a Data Device

ABSTRACT

A data device may have at least a magnetic lamination with a thermal retention structure deposited on a substrate and configured to maintain a predetermined temperature for a predetermined amount of time. Such predetermined temperature and amount of time may allow for the growth of a magnetic layer with a predetermined magnetic anisotropy.

SUMMARY

Various embodiments are generally directed to a data device. Accordingto some embodiments, a magnetic lamination can have at least a thermalretention structure deposited on a substrate and configured to maintaina predetermined temperature for a predetermined amount of time, whichmay allow for the growth of a magnetic layer with a predeterminedmagnetic anisotropy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides an exploded view of an exemplary data storage device.

FIG. 2 shows a block representation of selected portions of a datastorage device.

FIG. 3 display a block representation of a cross-section of an examplemagnetic lamination constructed in accordance with various embodiments.

FIG. 4 illustrates a block representation of a cross-section of anexample magnetic lamination constructed in accordance with variousembodiments.

FIG. 5 provides a block representation of a cross-section of an exampledata storage media capable of being used in the device of FIG. 1.

FIG. 6 graphs structural data corresponding with various embodiments ofan example magnetic lamination.

FIG. 7 provides a flowchart of an example magnetic laminationfabrication routine illustrative of steps carried out in accordance withvarious embodiments.

DETAILED DESCRIPTION

The present disclosure generally provides various embodiments of amagnetic lamination configured to retain heat for a predetermined amountof time. As the data storage industry progresses to increased datacapacity and faster data access, magnetic laminations are becoming achoke point for advancing data storage and retrieval. That is, whileseveral technologies are being advanced to increase the ability to writedata faster, such as heat assisted magnetic recording (HAMR), themagnetic capabilities of a recording lamination can limit how small andclose magnetic data bits can be placed with accurate data access. Assuch, there is continued industry demand for magnetic laminations thatcan handle increased data bit density while allowing reliable dataaccesses, especially in reduced form factor data storage devices.

Accordingly, a data storage media can be configured with at least athermal retention structure that is tuned with respect to a substrate tomaintain a predetermined temperature for a predetermined amount of time,which may allow the growth of a magnetic layer with a predeterminedmagnetic anisotropy. The retention of a particular amount of heat for aparticular length of time can allow for creation of high in-planeanisotropic magnetic layers at a rate that allows for commercialpracticality. In other words, heat may be applied in-situ to achievetemperatures for a given amount of time, but such activity isdetrimental to commercially producing numerous data storage media, suchas 1000 media per hour.

With the inclusion of at least a thermal retention structure to a datastorage media, the media can be tuned with respect to the underlyingsubstrate so that heat that is applied once, and for a short period oftime, can be retained and allow crystalline recording layer fabricationwithout continued application of heat from an external source.

FIG. 1 generally illustrates an example data transducing portion 100 ofa data storage device. The transducing portion 100 is shown in anenvironment in which various embodiments of a data storage media can bepracticed. It will be understood, however, that the various embodimentsof this disclosure are not so limited by the environment displayed inFIG. 1 and can be implemented in a variety of different data storagedevices.

The transducing portion 100 has first and second actuating assemblies102 and 104 each configured with a transducing head 106 positioned overprogrammed data bits 108 present on opposite surfaces 110 and 112 of asingle magnetic storage media 114. The storage media 114 is attached toa spindle motor 116 that rotates during use to produce an air bearingsurface (ABS) 118 on which a slider portion 120 of each actuatingassembly 102 and 104 flies to position a head gimbal assembly (HGA) 122,which includes the transducing heads 106, over a desired portion of themedia 114.

The transducing heads 106 can include one or more transducing elements,such as a magnetic writer and magnetically responsive reader, whichoperate to program and read data from the surfaces 110 and 112 of thestorage media 114, respectively. In this way, controlled motion of theactuating assemblies 102 and 104 may induce the transducers 106 to alignwith data tracks (not shown) defined on the storage media surfaces 110and 112 to write, read, and rewrite data.

FIG. 2 provides a block representation of portions of an example datatransducing assembly 130 that can be used in the data storage device 100of FIG. 1. The data transducing assembly 130 may be configured with atleast a transducing head 132 attached to a heating element 134, such asa laser, to heat an adjacent data storage media 136 across an airbearing 138. The transducing head 132 may have one or more data accesselements 140 that allow data to be programmed and read from the datastorage media.

The air bearing 138 can be passively and actively modulated to positionthe data access elements 140 a predetermined height above one or moredata bit locations as the data storage media 136 rotates. While notrequired to program or read data, the heating element 134 can beconfigured to temporarily modifying the magnetic coercivity of selectedregions of the data storage media 136 with an optical emitter 142adapted to discharge optical energy 144 to allow more efficient dataaccess with the data access elements 140.

With or without the use of the heating element 134, the data storagemedia 136 can be configured with an elevated magnetic coercivity andanisotropy, especially in-plane anisotropy, that allows data bits to becompressed into a smaller area, thus increasing data capacity. However,fabrication of data storage media with such elevated coercivity andanisotropy can correspond with the maintenance of high substratetemperatures, such as 400-800° C., which can be challenging to sustainwhile maintaining commercially viable media fabrication throughput.

FIG. 3 provides a block representation of a portion of an example datastorage media 150 that is capable of being tuned to sustain highsubstrate temperatures without continuous application of external heatduring fabrication. While a magnetic recording lamination can beconstructed in variety of different, non-limiting manners, the datastorage media 150 is formed on a substrate 152. The substrate 152 mayprovide structural properties, like surface roughness and heatconductance, that contribute to the growth and deposition of layers,such as the thermal retention structure 154.

It should be noted that the any number of intervening layers, like aseed layer, may be disposed between the substrate 152 and thermalretention structure 154 to promote the formation of various structuraland magnetic characteristics, but no such intervening layers arerequired or limited by the present disclosure. In various embodiments,the substrate 152 is comprised of materials with low thermalconductance, such as glass and glass ceramic composites, while otherembodiments use materials with large thermal conductance, such as Si,AlMg, and NiP.

While the choice of substrate material may be in response to a host ofdifferent reasons, like mechanical integrity and cost, the formation ofthe thermal retention structure 154 is tuned to compensate for thechosen substrate 152 material to provide predetermined structural andoperational characteristics, such as heat conductance and the subsequentgrowth of crystalline magnetic layers. For example, if a glass or classcomposite is used for the substrate 152, which has a low thermalconductance, the thermal retention structure 154 can be a continuousmagnetic film, such as Cu and Mo, that provides emissivity that allowsthe substrate 152 to retain predetermined amounts of thermal energy forpredetermined lengths of time.

The consideration of the material and structural characteristics of thesubstrate 152 provides the ability to tune the thickness 156, material,and emissivity of the thermal retention structure 154 so that heatapplied to the data storage media 150 in a single application isretained at a predetermined temperature, such as 400-800° C., for apredetermined amount of time, such as 3 ps-60 s, without the continuedapplication of heat in-situ to the substrate 152.

FIG. 4 displays a block representation of a cross-section of anotherexample data storage media 160 capable of being tuned to providepredetermined heat retention. The use of a substrate 162 material withhigh thermal conductance, such as Si and AlMg, can be accommodated bytuning the thermal retention structure 164 as a lamination of a thermaldiffusion barrier 166 and a magnetic film with tuned emissivity. Theconstruction of the thermal diffusion barrier 166, which can be anunlimited variety of materials that provide thermal diffusion, such asSiN and SiO₂, between the magnetic film 168 and the substrate 162 canallow the metallic film 168 to emit thermal energy without the substrate162 dissipating the heat too quickly due to elevated conductance.

As shown in FIGS. 3 and 4, the ability to tune the thermal retentionstructure 154 and 164 with respect to the substrate 152 and 162 canallow for the fabrication of magnetic recording layers that areconducive to high data bit density. That is, the tuned configuration ofthe thermal retention structure 154 and 164 with thicknesses 156, 170and 172 and materials that complement the substrate 152 and 162 allowsheat to be retained so that recording layers, such as high in-planeanisotropy (Ku) L₁₀-FePt and crystalline RE-Co alloys, can befabricated.

It should be noted that high in-plane anisotropic materials commonlycorrespond to elevated substrate temperatures for proper growth, whichis challenging with substrate materials that either conduct anddissipate heat, such as Si, or fail to conduct enough heat to maintainelevated temperatures over time, such as glass.

FIG. 5 generally illustrates a block representation of a portion of adata storage media 180 constructed in accordance with variousembodiments. While the data storage media 180 can permanently include asubstrate 182, some embodiments remove the substrate 182 subsequent toformation of the media 180 in its entirety. Regardless of whether thesubstrate 182 is removed or not, a thermal retention structure 184,which may be similar or dissimilar from the structures 154 and 164 ofFIGS. 3 and 4, is tuned with a thickness 186 and configuration withrespect to the substrate 182 and deposited thereon.

The formation of the thermal retention structure 184 may allow thedeposition and growth of a magnetic recording layer 188. Theconstruction of the recording layer 188 is not limited, but in someembodiments can be configured for perpendicular data recording withdiscrete data tracks and servo information. The recording layer 188 mayfurther be configured as a lamination of multiple layers withoutlimitation, such as a soft magnetic underlayer and interlayer(s), thatmay or may not be deposited and grown while the substrate 182 ismaintained at the predetermined elevated temperature.

While not required, the data storage media 180 may be formed with aprotective layer 190 disposed between the recording layer 188 andthermal retention structure 184 and constructed of a material, such asSiN and SiO₂, that has a thermal conductivity that allows data bitaccess in a variety of manners, like HAMR and perpendicular recording.The thicknesses of the various layers of the data storage media 180 canalso be tuned in response to the substrate 182 as well as the eventualmanner of data bit access. For example, the thermal retention structurethickness 186 can range from 30-200 nm and the protection layerthickness 192 can be between 1-20 nm.

FIG. 6 graphs example structural data 200 of a data storage media,specifically, the amount of heat retained by a substrate over time whena data storage media is constructed with a thermal retention structuretuned with respect to an underlying substrate. As shown, a brief initialapplication of heat, illustrated by region 202, brings the substrate toan elevated temperature. With a predetermined temperature thresholdbeing met during or after the application of heat, the external thermalsource is removed and the substrate maintains the elevated temperaturefor a predetermined period of time 204 that corresponds with the tuningof the thermal retention structure.

Eventually, the substrate cools, but the ability to maintain an elevatedtemperature with such a brief application of heat allows for moreefficient media fabrication as temperature monitoring and in-situ heatapplication is eliminated. As can be appreciated, the various tuningcapabilities of the thermal retention structure, such as thickness andmaterial, can allow for the precise control of the timed regions 202 and204 that can be adjusted to accommodate the fabrication of numerousdifferent magnetic layers that correspond to high substratetemperatures, such as high in-plane anisotropy layers.

FIG. 7 provides a flow chart for an example data storage mediaformatting routine 210 performed in accordance with various embodiments.The routine 210 may begin with any number of design decisions and stepsthat evaluate the purpose and structure of the data storage media todetermine various media characteristics, such as magnetic anisotropy,substrate material, and thermal retention structure configuration.

With at least substrate material, temperature, and heat retention timebeing determined, step 212 can tune the thermal retention structure tothe substrate material. Step 214 subsequently forms the thermalretention structure on the substrate. The thermal retention layer formedin step 214 may have one or many layers with common or dissimilarthicknesses and materials, as displayed in FIGS. 3 and 4, to allow thesubstrate to retain the predetermined temperature without continuousapplication of heat during formation of a magnetic recording layer.

Next, step 216 deposits a protective layer with low thermal conductanceonto the thermal retention layer. The protective layer may beconstructed to provide a blanket effect, of sorts, to contain heatemitted from the thermal retention layer to the substrate. Regardless ofthe purpose or configuration of the protective layer, step 218successively applies heat to the data storage media, including at leastthe thermal retention structure and substrate. The heat can be providedin any number of different manners that elevate the temperature of thesubstrate to the predetermined temperature, as generally illustrated byregion 202 in FIG. 6. In some embodiments, the thermal retentionstructure is elevated to the predetermined temperature and continuouslyemits heat to maintain the predetermined temperature in the substrateafter the external heat source is removed.

While the substrate is heated to the predetermined temperature, step 220deposits and grows a magnetic recording layer atop the protective layer.As discussed above, the continued elevated temperature of the substratecan allow for high in-plane anisotropic magnetic layers to be formed instep 220. However, not all layers of the magnetic recording layer mustbe deposited while the substrate is above the predetermined temperature.That is, some magnetic recording sub-layers may be formed while thesubstrate is below the predetermined temperature, depending on thechosen design and purpose of the data storage media.

The various steps of routine 210 can provide a data storage media tunedwith respect to structural and operational characteristics. However, theroutine 210 is not limited to the steps provided in FIG. 7. That is, thevarious aspects of the routine 210 can be altered, moved, and omittedwithout deterring from the spirit of the present disclosure.Furthermore, any number of steps and decisions can be added to theroutine 210 to more succinctly provide the manner in which a datastorage media can be made and used.

It is particularly noted that the various embodiments illustrated in thepresent disclosure can provide data storage media capable of retainingheat and provide a substrate temperature conducive to growing highmagnetic anisotropic layers capable of increasing data bit density.Moreover, the ability to tune the thermal retention structure tomaintain a predetermined substrate temperature over time allowsefficient media production as external heat can quickly be applied andremoved without having to provide continued application and monitorsubstrate temperature. It will be appreciated that the variousembodiments discussed herein have numerous potential applications andare not limited to a certain field of electronic media or type of datastorage devices.

It is to be understood that even though numerous characteristics andadvantages of various embodiments have been set forth in the foregoingdescription, together with details of the structure and function ofvarious embodiments, this detailed description is illustrative only, andchanges may be made in detail, especially in matters of structure andarrangements of parts within the principles of the present disclosure tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

What is claimed is:
 1. A device comprising: a thermal retentionstructure tuned with respect to a substrate to configure to maintain apredetermined temperature range for at least a predetermined amount oftime to allow the growth of a magnetic layer with a predeterminedmagnetic anisotropy.
 2. The device of claim 1, wherein the predeterminedtemperature range is 400-600 degrees Celsius.
 3. The device of claim 1,wherein the predetermined time corresponds to a material construction ofthe thermal retention structure.
 4. The device of claim 1, wherein thepredetermined magnetic anisotropy corresponds to a heat assistedmagnetic recording (HAMR).
 5. The device of claim 1, wherein the thermalretention structure is deposited on a glass substrate.
 6. The device ofclaim 1, wherein the thermal retention structure is deposited on athermally conductive substrate.
 7. The device of claim 1, wherein thethermal retention structure has a protective layer with a first thermalconductance.
 8. The device of claim 7, wherein the thermal retentionstructure has a metallic film with a second thermal conductance,different from the first thermal conductance.
 9. The device of claim 8,wherein the thermal retention structure has a thermal diffusion barrierwith a third thermal conductance, less than the first and second thermalconductance.
 10. The device of claim 9, wherein the protective layer andthermal diffusion barrier are both a Silicon compound and the metallicfilm is a single metal.
 11. The device of claim 9, wherein theprotective layer and thermal diffusion barrier are positioned onopposite sides of the metallic film.
 12. The device of claim 10, whereinthe protective layer and thermal diffusion barrier are different Siliconcompounds.
 13. The device of claim 10, wherein the protective layer andthermal diffusion barrier each have thicknesses less than a metalthickness of the metallic film.
 14. A method comprising: tuning athermal retention structure with respect to a substrate, the thermalretention structure configured to maintain a predetermined temperaturefor a predetermined amount of time; and growing a magnetic layer with apredetermined magnetic anisotropy concurrently with the predeterminedtemperature and amount of time.
 15. The method of claim 14, furthercomprising applying heat to the thermal retention structure, the heatinducing the predetermined temperature before the heat is removed andthe magnetic layer is grown.
 16. The method of claim 14, furthercomprising annealing the magnetic recording layer with the applicationof laser radiation.
 17. The method of claim 14, wherein thepredetermined time can be up to a 60 seconds.
 18. The method of claim14, wherein the predetermined amount of time and temperature correspondto the substrate to provide a predetermined thermal saturation profile.19. A method comprising: selecting a temperature and amount of time inresponse to a substrate; depositing a thermal retention structure on thesubstrate, the thermal retention structure configured to maintain thetemperature for the amount of time; and growing a magnetic layer with apredetermined magnetic anisotropy concurrently with the maintenance ofthe temperature and amount of time.
 20. The method of claim 19, whereinthe predetermined magnetic anisotropy corresponds with heat assistedmagnetic recording (HAMR) of data to the magnetic layer.